HI William This is for both on and off grid correct? jay
> On Oct 29, 2025, at 10:34 AM, William Bryce via RE-wrenches > <[email protected]> wrote: > > Hi Dave > > The AC wires need to be the same size and try to have the same length. This > is important because the inverter when stacked "shares" the power so you want > to try to prevent any imbalance in voltage and resistance issues, or circle > issues. > > In older stacked systems you have a master and a slave and when the power > demand increases then the slave would take the excess. On AIO's the power is > shared equally all the time (this is a good thing as you don't get the > flicker as the slave picks up). It is important that the install takes into > account the different way the power is used and delivered. Have a clean > install, with the correct sized conductors as specified by the manufacturer, > and try to keep the wire run short and equal when connecting the inverter AC > runs together. > > On Wed, Oct 29, 2025 at 9:41 AM Dave Tedeyan via RE-wrenches > <[email protected] > <mailto:[email protected]>> wrote: >> William this is really good information, thanks for sharing the technical >> perspective. >> >> I have two sites with two of these inverters and both of them are exhibiting >> very similar behavior. On Friday, I was out at the other one to wrap up a >> few things. While I was out there I verified some of the things that Midnite >> tech support suggested like making sure that the AC wires to each inverter's >> grid in and cables are the same length and also from the battery bus bar to >> each inverter are the same length. This was actually a bit surprising to me, >> considering with lead acid it is more important to have the battery cables >> from the bus bar to the batteries be the exact same length and the cables to >> the inverters did not matter as much. >> >> Based on what we were talking about last week, I removed the N-G bond in the >> disconnect for the solar, but I have not yet gone looking for other N-G >> connections in the way that Jason suggested. I have not gotten a CA-DC link >> overvoltage error, but I have still seen some of the symptoms. It is not as >> bad as the other site, but what I notice on the monitoring is that in the >> late afternoon/early evening one inverter shows an unreasonable amount of >> solar (with power going into the grid and into the battery), while the other >> inverter shows low solar (with a ton of power coming out of the battery >> going to the load and the grid), and the battery SOC drops very quickly down >> to the discharge end SOC (on grid) setting of 85%. >> Jason and William, do you know whether any faulty wiring with N-G connected >> in loads on the non-backed up side will affect the system the same way? Or >> is it mostly just important to check for any neutrals connected to ground on >> the backed up loads side? >> >> Jason, as to why a supply side connection - I was under the impression that >> a Power Control System just effectively limits the amount of power that can >> be sold to the grid. But on a standard 200A service, that limits you to >> about 7.7kw of sell back. I would not want to limit the system that much for >> a roughly 20kw system, even if more than the 7.7kw can go to powering loads >> and battery charging. In the Midnite monitoring, it is pretty easy to limit >> the grid sell back with the "maximum feed in grid power" in the Power >> Control settings. >> >> Cheers, >> Dave >> >> On Sun, Oct 26, 2025 at 8:51 AM William Bryce via RE-wrenches >> <[email protected] >> <mailto:[email protected]>> wrote: >>> All >>> >>> Most modern all-in-one (AIO) inverters are designed around a non-isolated >>> high-voltage DC bus. This design is what allows manufacturers to advertise >>> higher output numbers — for example, “15–18 kW” — while the inverter may >>> only deliver 12 kW during nighttime operation when PV isn’t contributing >>> (it is also cheaper to build). Without the shared non-isolated DC link, >>> these power-boosted daytime ratings wouldn’t be possible. >>> >>> A DC-bus overvoltage fault almost always points to one of two issues: >>> >>> Improper system design >>> >>> Wiring and installation mistakes >>> >>> Off-Grid Example >>> >>> A common DIY mistake is pairing a large solar array (because glass is >>> cheap) with a relatively small battery (not as cheap). >>> When the battery is full and a large load suddenly turns off, the excess >>> energy has nowhere to go. The inverter throttles back, but the stored >>> energy can still push the DC-bus voltage up rapidly. If the inverter didn’t >>> protect itself, the capacitors would be at risk — so it shuts down with an >>> overvoltage error. This is also common when using a large retrofitted AC >>> coupled array. >>> >>> Grid-Tie Example >>> >>> In grid-connected systems, DC-bus overvoltage is typically caused by wiring >>> mistakes, some common examples are: >>> >>> Multiple neutral-to-ground bonds >>> >>> Reversed hot/neutral at outlets >>> >>> A single inverter is usually more forgiving. However, stacked inverters >>> must share phase, neutral, and grounding relationships precisely. Any >>> mis-wiring can create circulating currents. That circulating energy is not >>> accounted for in the inverter’s internal power calculations, so the DC-bus >>> voltage rises unexpectedly — and the inverter shuts down for protection. >>> >>> A DC Link Overvoltage error is usually not an inverter defect — it’s a >>> system design or system wiring problem 99% of the time. Ensuring proper >>> neutral/ground bonding, correct polarity, adequate battery capacity, and >>> proper commissioning is critical to reliable AIO operation. >>> >>> This behavior is not unique to the MN AIO — all AIO inverters using a >>> non-isolated DC-bus topology share the same fundamental protection >>> limitations. >>> >>> Inverters are getting more complex to deal with the new rules and utility >>> requirements, this causes reliability issues as we move (or pushed) to full >>> integration with the grid. Because you know we all want the utility to >>> have full control over our systems! >>> >>> >>> On Sat, Oct 25, 2025 at 9:51 AM Jay via RE-wrenches >>> <[email protected] >>> <mailto:[email protected]>> wrote: >>>> I had an issue with a EG4 inverter and tech support was an insistent that >>>> there was multiple ground neutral bonds in the system. Fully off grid >>>> system with no generator. >>>> It wasn’t the issue but it seems like these inverters are sensitive to it. >>>> >>>> Is the inverter internally bonded, not that I’m aware of or what I’ve >>>> measured. >>>> And so I can’t figure out what it’s measuring between N/G to have a >>>> potential issue. >>>> >>>> Maybe someone can explain? >>>> >>>> Jay >>>> >>>> >>>> >>>>> On Oct 24, 2025, at 6:49 PM, Dave Tedeyan via RE-wrenches >>>>> <[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>> >>>>> >>>>> Thanks all for your thoughts here. It seems that the general consensus so >>>>> far is that the N-G should be bonded in the solar main disconnecting >>>>> means when doing a supply side connection (even if it is not technically >>>>> a separate service). When talking with Midnite Power, we made it very >>>>> clear that we were talking about a N-G bond in the inverter combiner / >>>>> solar main disconnect, and not the backed up loads panel. And being that >>>>> NY is still on 2017 code (only going to 2020 next year), with the >>>>> ambiguity in the code I am probably okay to undo the N-G connection in >>>>> the main solar disconnect. >>>>> >>>>> In this case specifically, we are backing up only a small subset of loads >>>>> in the house. The reason for the two inverters is because there is about >>>>> 24kw of solar. There is also a manual transfer switch to normally be able >>>>> to power the loads off the inverters, but to be able to switch to >>>>> powering the loads off the main panel in case of service needed on the >>>>> inverters. The neutrals in this system are all connected together, and I >>>>> am not sure if that could cause issues. It is probably difficult to >>>>> explain all the details in words, so I am copying part of the three line >>>>> diagram here. The second picture is the conductor and conduit schedule. >>>>> >>>>> Tom, I get it that the error sounds like it is on the DC side based on >>>>> the words, but when I talked to Midnite about it they were pretty clear >>>>> about it being due to multiple N-G bonds and they did not mention that it >>>>> could have anything to do with the DC side. >>>>> >>>>> Jason, that is a good idea as well to check the loads that got moved over >>>>> to see if there are any other inadvertent N-G bonds on the premises. This >>>>> also similar to what Midnite suggested, which was to lift the N-G bond in >>>>> the main panel and then see if they are still bonded somewhere else. It >>>>> seems like it can be a slow process to track that down with power cut to >>>>> the house, but that might be what I have to try if removing the N-G bond >>>>> in the solar main disconnect does not help. >>>>> >>>>> So, my main questions to anyone who has an opinion here are two fold: >>>>> 1. Do you bond the N-G in general in the main solar disconnect for a >>>>> supply side connection? >>>>> 2. Specifically with the Midnite AIO inverters, has anyone else had >>>>> issues with this "CA-DC link Overvoltage error" due to having a second >>>>> N-G bond in the house? (one in the main service panel, and one in the >>>>> solar main disconnect if it is a supply side connection). Or have you >>>>> seen this error and found that it was caused by something else? >>>>> >>>>> Cheers, >>>>> Dave >>>>> >>>>> >>>>> >>>>> On Thu, Oct 23, 2025 at 5:25 PM Jason Szumlanski via RE-wrenches >>>>> <[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>>> I agree. It is not a separate service. It is a "tap" of the existing >>>>>> service (I use that term loosely here). The additional service >>>>>> disconnect for the supply side interconnection should have L1, L2, and N >>>>>> connected ahead of the premises main disconnect with no EGC. There >>>>>> should be a N-G bonding jumper in the PV service disconnect. Then there >>>>>> should be no N-G bonds downstream of both the premises main disconnect >>>>>> and the PV service disconnect. >>>>>> >>>>>> Basically, it's the same as two main disconnects running from a meter >>>>>> enclosure. Each of the service disconnects has a N-G bond required. >>>>>> >>>>>> Some AHJs (the crazy ones) require an EGC between the enclosure where >>>>>> the supply side connection is made and the PV service disconnect. This >>>>>> creates a parallel fault path, and should not be allowed, in my humble >>>>>> opinion. >>>>>> >>>>>> Now it sounds like you might be doing a partial home backup. The issue >>>>>> there is that sometimes the loads or enclosures you moved over the >>>>>> backup load panel have inadvertent N-G bonds. Sometimes it's as simple >>>>>> as someone who got creative and used a ground as a neutral in a switch >>>>>> box. I say simple, but that can be hard to track down. >>>>>> >>>>>> When Midnite said to remove it from the inverter distribution panel, >>>>>> they were probably talking about the protected loads panel. >>>>>> >>>>>> I think more information is needed. >>>>>> >>>>>> >>>>>> >>>>>> Jason Szumlanski >>>>>> Principal Solar Designer | Florida Solar Design Group >>>>>> NABCEP Certified Solar Professional (PVIP) >>>>>> Florida State Certified Solar Contractor CVC56956 >>>>>> Florida Certified Electrical Contractor EC13013208 >>>>>> >>>>>> >>>>>> On Thu, Oct 23, 2025 at 11:03 AM Tyrone Houck via RE-wrenches >>>>>> <[email protected] >>>>>> <mailto:[email protected]>> wrote: >>>>>>> My interpretation, and the way it was explained to me by both Ryan >>>>>>> Mayfield and Kyle Bolger(several years ago at this point, popular >>>>>>> opinion may have changed since). Is that it is not a seperate service. >>>>>>> It is however required to have a ground-neutral bond( though in my >>>>>>> opinion pointless and redundant as there is a bond in the enclosure >>>>>>> where the tap is made). If it gives you any issue, ensure as close to >>>>>>> equal potential to the grounding electrode as possible(and make sure >>>>>>> your neutral is appropriately sized). I personally don't see the point >>>>>>> but it is an NEC requirement >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Thu, Oct 23, 2025, 6:08 AM Dave Tedeyan via RE-wrenches >>>>>>> <[email protected] >>>>>>> <mailto:[email protected]>> wrote: >>>>>>>> Hi All, >>>>>>>> >>>>>>>> For years I have understood that when doing a supply side connection, >>>>>>>> you are supposed to bond the neutral to ground in the solar service >>>>>>>> disconnect. I have a Midnite AIO system with two inverters (set up as >>>>>>>> a supply side connection) that recently was getting a CA-DC link >>>>>>>> Overvoltage error. When talking to Midnite, their first response was >>>>>>>> to make sure that there was only one N-G bond in the whole system. >>>>>>>> When I mentioned that the solar is a separate service and thus there >>>>>>>> is a N-G bond in both the main panel and the inverter distribution >>>>>>>> panel, they said to remove it from the inverter distribution panel. I >>>>>>>> want to make the system work right, but I also am hesitant to do >>>>>>>> something against how I have understood the NEC to be for a long time. >>>>>>>> I am curious if you all have thoughts on this or run into a similar >>>>>>>> situation. >>>>>>>> >>>>>>>> Cheers, >>>>>>>> Dave >>>>>>>> >>>>>>>> -- >>>>>>>> >>>>>>>> <https://www.sungineersolar.com/> >>>>>>>> Dave Tedeyan, P.E. >>>>>>>> Owner | Sungineer Solar >>>>>>>> p: he | him | his >>>>>>>> a: 1653 Slaterville Rd. >>>>>>>> <https://www.google.com/maps/search/1653+Slaterville+Rd.+%C2%A0+%7C%C2%A0Ithaca,+NY+14850?entry=gmail&source=g> >>>>>>>> >>>>>>>> <https://www.google.com/maps/search/1653+Slaterville+Rd.+%C2%A0+%7C%C2%A0Ithaca,+NY+14850?entry=gmail&source=g>| >>>>>>>> Ithaca, NY 14850 >>>>>>>> <https://www.google.com/maps/search/1653+Slaterville+Rd.+%C2%A0+%7C%C2%A0Ithaca,+NY+14850?entry=gmail&source=g> >>>>>>>> w: www.sungineersolar.com <http://www.sungineersolar.com/> >>>>>>>> c: (607) 270-0370 >>>>>>>> _______________________________________________ >>>>>>>> List sponsored by Redwood Alliance >>>>>>>> >>>>>>>> Pay optional member dues here: http://re-wrenches.org >>>>>>>> <http://re-wrenches.org/> >>>>>>>> >>>>>>>> List Address: [email protected] >>>>>>>> <mailto:[email protected]> >>>>>>>> >>>>>>>> Change listserver email address & settings: >>>>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>>>>>> >>>>>>>> There are two list archives for searching. When one doesn't work, try >>>>>>>> the other: >>>>>>>> https://www.mail-archive.com/[email protected]/ >>>>>>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>>>>>> >>>>>>>> List rules & etiquette: >>>>>>>> http://www.re-wrenches.org/etiquette.htm >>>>>>>> >>>>>>>> Check out or update participant bios: >>>>>>>> http://www.members.re-wrenches.org >>>>>>>> <http://www.members.re-wrenches.org/> >>>>>>>> >>>>>>> _______________________________________________ >>>>>>> List sponsored by Redwood Alliance >>>>>>> >>>>>>> Pay optional member dues here: http://re-wrenches.org >>>>>>> <http://re-wrenches.org/> >>>>>>> >>>>>>> List Address: [email protected] >>>>>>> <mailto:[email protected]> >>>>>>> >>>>>>> Change listserver email address & settings: >>>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>>>>> >>>>>>> There are two list archives for searching. When one doesn't work, try >>>>>>> the other: >>>>>>> https://www.mail-archive.com/[email protected]/ >>>>>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>>>>> >>>>>>> List rules & etiquette: >>>>>>> http://www.re-wrenches.org/etiquette.htm >>>>>>> >>>>>>> Check out or update participant bios: >>>>>>> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >>>>>>> >>>>>> _______________________________________________ >>>>>> List sponsored by Redwood Alliance >>>>>> >>>>>> Pay optional member dues here: http://re-wrenches.org >>>>>> <http://re-wrenches.org/> >>>>>> >>>>>> List Address: [email protected] >>>>>> <mailto:[email protected]> >>>>>> >>>>>> Change listserver email address & settings: >>>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>>>> >>>>>> There are two list archives for searching. When one doesn't work, try >>>>>> the other: >>>>>> https://www.mail-archive.com/[email protected]/ >>>>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>>>> >>>>>> List rules & etiquette: >>>>>> http://www.re-wrenches.org/etiquette.htm >>>>>> >>>>>> Check out or update participant bios: >>>>>> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >>>>>> >>>>> >>>>> <PV3.0 as built.jpg> >>>>> <PV3.1 as built.jpg> >>>>> _______________________________________________ >>>>> List sponsored by Redwood Alliance >>>>> >>>>> Pay optional member dues here: http://re-wrenches.org >>>>> <http://re-wrenches.org/> >>>>> >>>>> List Address: [email protected] >>>>> <mailto:[email protected]> >>>>> >>>>> Change listserver email address & settings: >>>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>>> >>>>> There are two list archives for searching. When one doesn't work, try the >>>>> other: >>>>> https://www.mail-archive.com/[email protected]/ >>>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>>> >>>>> List rules & etiquette: >>>>> http://www.re-wrenches.org/etiquette.htm >>>>> >>>>> Check out or update participant bios: >>>>> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >>>>> >>>> _______________________________________________ >>>> List sponsored by Redwood Alliance >>>> >>>> Pay optional member dues here: http://re-wrenches.org >>>> <http://re-wrenches.org/> >>>> >>>> List Address: [email protected] >>>> <mailto:[email protected]> >>>> >>>> Change listserver email address & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> There are two list archives for searching. When one doesn't work, try the >>>> other: >>>> https://www.mail-archive.com/[email protected]/ >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> >>>> List rules & etiquette: >>>> http://www.re-wrenches.org/etiquette.htm >>>> >>>> Check out or update participant bios: >>>> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >>>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> Pay optional member dues here: http://re-wrenches.org >>> <http://re-wrenches.org/> >>> >>> List Address: [email protected] >>> <mailto:[email protected]> >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> There are two list archives for searching. When one doesn't work, try the >>> other: >>> https://www.mail-archive.com/[email protected]/ >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> http://www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >>> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> <http://re-wrenches.org/> >> >> List Address: [email protected] >> <mailto:[email protected]> >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
